Add base gen tests for list matching compilation

crates/compiler/test_gen/src/gen_list.rs

@@ -3578,3 +3578,102 @@ fn list_walk_from_even_prefix_sum() {
         i64
     );
 }
+
+#[cfg(any(feature = "gen-llvm", feature = "gen-wasm"))]
+mod pattern_match {
+    #[cfg(feature = "gen-llvm")]
+    use crate::helpers::llvm::assert_evals_to;
+
+    #[cfg(feature = "gen-wasm")]
+    use crate::helpers::wasm::assert_evals_to;
+
+    use super::RocList;
+
+    #[test]
+    fn unary_exact_size_match() {
+        assert_evals_to!(
+            r#"
+            helper = \l -> when l is
+                [] -> 1u8
+                _ -> 2u8
+
+            [ helper [], helper [{}] ]
+            "#,
+            RocList::from_slice(&[1, 2]),
+            RocList<u8>
+        )
+    }
+
+    #[test]
+    fn many_exact_size_match() {
+        assert_evals_to!(
+            r#"
+            helper = \l -> when l is
+                [] -> 1u8
+                [_] -> 2u8
+                [_, _] -> 3u8
+                [_, _, _] -> 4u8
+                _ -> 5u8
+
+            [ helper [], helper [{}], helper [{}, {}], helper [{}, {}, {}], helper [{}, {}, {}, {}] ]
+            "#,
+            RocList::from_slice(&[1, 2, 3, 4, 5]),
+            RocList<u8>
+        )
+    }
+
+    #[test]
+    fn ranged_matches_head() {
+        assert_evals_to!(
+            r#"
+            helper = \l -> when l is
+                [] -> 1u8
+                [A] -> 2u8
+                [A, A, ..] -> 3u8
+                [A, B, ..] -> 4u8
+                [B, ..] -> 5u8
+
+            [
+                helper [],
+                helper [A],
+                helper [A, A], helper [A, A, A], helper [A, A, B], helper [A, A, B, A],
+                helper [A, B], helper [A, B, A], helper [A, B, B], helper [A, B, A, B],
+                helper [B], helper [B, A], helper [B, B], helper [B, A, B, B],
+            ]
+            "#,
+            RocList::from_slice(&[
+                1, //
+                2, //
+                3, 3, 3, 3, //
+                4, 4, 4, 4, //
+                5, 5, 5, 5, //
+            ]),
+            RocList<u8>
+        )
+    }
+
+    #[test]
+    fn bind_variables() {
+        assert_evals_to!(
+            r#"
+            helper : List U8 -> U8
+            helper = \l -> when l is
+                [] -> 1u8
+                [x] -> x
+                [x, y, ..] -> x * y
+
+            [
+                helper [],
+                helper [5],
+                helper [3, 5], helper [3, 5, 7], helper [3, 5, 7, 11],
+            ]
+            "#,
+            RocList::from_slice(&[
+                1, //
+                5, //
+                15, 15, 15 //
+            ]),
+            RocList<u8>
+        )
+    }
+}